Chronological renal resistive index increases related to atherosclerotic factors, and effect of renin-angiotensin system inhibitors

Association of renal resistive indices with kidney disease progression and mortality

BACKGROUND

Renal resistive indices (RRI) have been shown to predict the progression of kidney disease. This study aims to evaluate the association of RRI with mortality and dialysis initiation after adjustment to therapeutic and life style interventions.

METHODS

This is a retrospective study that included all chronic kidney disease patients followed for at least two years in three nephrology clinics between 2006 and 2019 and who had a RRI level in their files. Kaplan Meier and log rank test compared the survival of patients with normal versus high RRI. Cox regression analysis evaluated the association between RRI and death or dialysis initiation after adjustment to treatments and life style modifications.

RESULTS

A total of 192 patients were analyzed: 68 had RRI < 0.7 and 124 had RRI ≥ 0.7. Their mean age was 66.5 ± 13.1 years at first visit, 78.1% were males. There was a negative correlation between baseline eGFR and RRI (p < 0.001; Spearman correlation coefficient = -0.521). The survival was significantly better in patients with RRI < 0.7 with a Log Rank test < 0.001. The univariate cox regression analysis showed a significant association between RRI and mortality (HR = 1.08; 95%CI: 1.04-1.11; p < 0.001) that remained significant after adjustment to cardiovascular risk factors and interventions such as salt reduction, blood pressure control, statins and RAAS inhibitors (HR = 1.04; 95%CI: 1.00-1.08; p = 0.036). Cox regression analysis showed a significant association between RRI and dialysis initiation (HR = 1.06; 95%CI 1.01-1.10; p = 0.011).

CONCLUSION

Our study revealed that patients with an elevated RRI ≥ 0.7 are at a higher risk of mortality after adjustment to medications and lifestyle modifications. RRI can, according to this study, be considered as an independent prognostic factor in CKD patients.

Favorable effect of renal denervation on elevated renal vascular resistance in patients with resistant hypertension and type 2 diabetes mellitus

Objective

To assess the effect of renal denervation (RDN) on renal vascular resistance and renal function in patients with drug-resistant hypertension (HTN) and type 2 diabetes mellitus (T2DM).

Materials and methods

Fifty-nine patients (mean age 60.3 ± 7.9 years, 25 men) with resistant HTN [mean 24-h ambulatory blood pressure (BP) 158.0 ± 16.3/82.5 ± 12.7 mmHg, systolic/diastolic] and T2DM (mean HbA1c 7.5 ± 1.5%) were included in the single-arm prospective study and underwent RDN. Renal resistive index (RRI) derived from ultrasound Doppler; estimated glomerular filtration rate (Chronic Kidney Disease Epidemiology Collaboration formula), office and 24-h ambulatory BP were measured at baseline, 6, and 12 months after RDN to evaluate the respective changes in renal vascular resistance, renal function, and BP during treatment.

Results

Forty-three patients completed 12 months follow-up. The RRI changed depending on the baseline value. Specifically, the RRI decreased significantly in patients with elevated baseline RRI values ≥ 0.7 {n = 23; -0.024 [95% confidence interval (CI): -0.046, -0.002], p = 0.035} and did not change in those with baseline RRI < 0.7 [n = 36; 0.024 (95% CI: -0.002, 0.050), p = 0.069]. No significant change was observed in eGFR whereas BP was significantly reduced at 12 months after RDN by -10.9 (95% CI: -16.7, -5.0)/-5.5 (95% CI: -8.7, -2.4) mmHg, systolic/diastolic. No relationship was found between the changes in RRI and BP.

Conclusion

Our study shows that RDN can decrease elevated renal vascular resistance (RRI > 0.7) and stabilize kidney function in patients with RHTN and T2DM independently of its BP-lowering effect.

Prognostic significance of the renal resistive index in the primary prevention of type II diabetes

The renal resistive index has been demonstrated to predict the progression of renal disease and recurrence of major cardiac events in high-risk cardiovascular patients, in addition to other comorbidities. We aimed to assess the prognostic significance of the renal resistive index in type 2 diabetic patients for primary prevention. From 2008 to 2011, patients with type 2 diabetes underwent cardiovascular evaluation, including renal resistive index assessment by renal Doppler ultrasound. The incidence of all-cause death, cardiovascular events, dialysis requirement or a twofold increase in creatinine was recorded. Survival curves were estimated by the Kaplan-Meier method. Two hundred sixty-six patients were included; 50% of the patients were men, an HbA1C level of 8.1 ± 1.7% (65 ± 13.6 mmol/mol) and a serum creatinine level of 8 [7-9] mg/L. The mean 24-hour systolic blood pressure, 24-hour diastolic blood pressure, and 24-hour pulse pressure were 133.4 ± 16.7, 76.5 ± 9.4, and 56.9 ± 12.4 mm Hg, respectively. The median renal resistive index was 0.7 [0.6-0.7] with a threshold of 0.7 predictive of monitored events. After adjustment of the 24-hour pulse pressure, age and 24-hour heart rate, a renal resistive index ≥0.70 remained associated with all-cause death (hazard ratio: 3.23 (1.16-8.98); P = .025) and the composite endpoint of major clinical events (hazard ratio: 2.37 (1.34-4.18); P = .003). An elevated renal resistive index with a threshold of 0.7 is an independent predictor of a first cardiovascular or renal event in type 2 diabetic patients. This simple index should be implemented in the multiparametric staging of diabetes.

The renal resistive index as a new complementary tool to predict microvascular diabetic complications in children and adolescents: a groundbreaking finding

The increasing prevalence of type 1 diabetes mellitus (DM) has made it necessary to have new markers for early detection of diabetic nephropathy. Renal resistive index (RI) by using renal Doppler can be a helpful tool in detecting functional alterations in renal hemodynamics. This study was conducted on 100 children and adolescents with type 1 DM. They were further subdivided into two equal subgroups: group 1 with type 1 DM and normo-albuminuria [urinary albumin excretion (UAE) <30 mg/24 hours], and group 2 with type 1 DM and hyper-albuminuria (increased UAE >30 mg/24 hours). There were 37 males (37%) and 63 females (63%); their mean ages were 13.6±2.53 (range, 10-19) years and mean disease duration was 8.867±2.260 (range, 5-13) years. Progressive increase in RI was significantly associated with increased disease duration more than 10 years, elevated serum HbA1c more than 7.5% and early pubertal stages. While not significantly related to sex, weight, height, blood pressure or serum lipid profile, diabetic micro-vascular complications (nephropathy and sensory neuropathy) were more prevalent among patients with RI more than 0.58. Renal RI could be a useful complementary test for the evaluation of functional alterations in renal hemodynamics in the early stages of diabetic nephropathy.